code: def add_mock_user(
      root_domain_client, user_stash: UserStash, user: User
  ) -> User:
      # prepare: add mock data
      result = user_stash.partition.set(
          root_domain_client.credentials.verify_key, user
      )
      assert result.is_ok()
  
      user = result.ok()
      assert user is not None
  
      return user
  
file_path: PySyft/packages/syft/tests/syft/users/user_stash_test.py
imports: from faker import Faker
  from syft.node.credentials import SyftSigningKey
  from syft.service.response import SyftSuccess
  from syft.service.user.user import User
  from syft.service.user.user import UserUpdate
  from syft.service.user.user_roles import ServiceRole
  from syft.service.user.user_stash import UserStash
  from syft.types.uid import UID
label_desc: Use image node_id 1 for calling a global function with example usage: add_mock_user(root_domain_client, user_stash, user) and returns: user